Dead Vizio M43-C1

[garry7263]

Have a dead 43 inch Vizio 4k TV

I measured the voltage at the connector. Getting 19 volts at the 12 pins and with the main board connected I get the standby voltage. I get the 19 volts with the other boards disconnected.

I hope there is some protection from over voltage on the main board. Don't want to do anything else till I can get the 12 volt pins reading 12 volts.

[neilc6]

Re: Dead Vizio M43-C1

19V at 12V pin is red herring. Just mislabelled. Check for ps-on and b-lon signals

https://www.badcaps.net/forum/showthread.php?t=76708

[nomoresonys]

Re: Dead Vizio M43-C1

Do test number 3 below try to do it just as instructed.

[garry7263]

Re: Dead Vizio M43-C1

plugged in:

BL_OFF/ON ( .001v ) | DIM ( .010v )
3D_ON ( .000v ) | PS_ON ( .075v )
GND ( .000v ) | GND ( .000v )
GND ( .000v ) | GND ( .000v )
+12V_A ( +19.03v ) | +12V_A ( +19.03v )
+12V ( +19.03v ) | +12V ( +19.03v )
+12V ( +19.03v ) | +12V ( +19.03v )
+5V/+3.5V ( +5.16v ) | +5V/+3.5V ( +5.16v )

Turned on:

BL_OFF/ON ( .107v ) | DIM ( 3.333v )
3D_ON ( .009v ) | PS_ON ( 3.690v )
GND ( .009v ) | GND ( .009v )
GND ( .009v ) | GND ( .009v )
+12V_A ( +18.98v ) | +12V_A ( +18.98v )
+12V ( +18.98v ) | +12V ( +18.98v )
+12V ( +18.98v ) | +12V ( +18.98v )
+5V/+3.5V ( +5.14v ) | +5V/+3.5V ( +5.14v )

I checked the voltage without the main board plugged in. Same readings but 0.00v on the standby voltages. Shouldn't they read 5 volts leaving the power board to provide 5v to the main board for standby?

Obviously .107v is not enough to turn on the backlights.

[nomoresonys]

Re: Dead Vizio M43-C1

Yes, recheck, doesn't make any sense unless those aren't the standby, maybe unplug the backlights from powerboard and see if those voltages come back??

[garry7263]

Re: Dead Vizio M43-C1

Finally got around to checking again. Looking at the back of the board, that standby voltage must only come from the main board because there is nothing connected to it. Very short trace that leads to no components at all. So must be either the main board or the backlights. Will pull apart the screen and check them at least to eliminate them.

[nomoresonys]

Re: Dead Vizio M43-C1

"Obviously .107v is not enough to turn on the backlights" yep, that signal comes from the mainboard, good video on testing there: https://www.youtube.com/watch?v=ocqnqmBxiqY

[R_J]

Re: Dead Vizio M43-C1

The BL_ON/OFF and DIM on the power supply are used on this tv, the led driver board is controlled directly from the main board via CN805. It is not a simple ON/OFF signal, there are data signals that control the 14 led drivers. Check that you have DC (18V?) voltage on CN804 of the driver board.

[nomoresonys]

Re: Dead Vizio M43-C1

Well is it a typo? "the BL_on/off and DIM ARE OR ARE NOT used??

[budm]

Re: Dead Vizio M43-C1

This version of power supply board assembly does not have Backlights circuit, you can see that backlight section of the power supply board is not stuffed with parts, so this power supply board only supplies the running Voltage to the LED driver board, that is why the BL-ON/DIM control are not used on this power supply board, the main board controls the LED driver board directly.

[nomoresonys]

Re: Dead Vizio M43-C1

Thanks Bud.